Power factor correction circuit

ABSTRACT

The present invention discloses a power factor correction circuit. The power factor correction circuit includes: a first bridge arm having a first switch and a second switch; a second bridge arm having a third switch and a fourth switch; a first inductor and a second inductor; a first capacitor and/or a second capacitor connected with a common point between the second inductor and the first inductor; and a third capacitor and/or a fourth capacitor, the third capacitor connected in parallel to the third switch based on an arrangement of the second capacitor and having a capacitance value same as that of the second capacitor, the fourth capacitor connected in parallel to the fourth switch based on an arrangement of the first capacitor and having a capacitance value same as that of the first capacitor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No. 202020888717.5 filed in P.R. China on May 22, 2020, the entire contents of which are hereby incorporated by reference.

Some references, if any, which may include patents, patent applications and various publications, may be cited and discussed in the description of this invention. The citation and/or discussion of such references, if any, is provided merely to clarify the description of the present invention and is not an admission that any such reference is “prior art” to the invention described herein. All references listed, cited and/or discussed in this specification are incorporated herein by reference in their entireties and to the same extent as if each reference was individually incorporated by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a power factor correction circuit, and particularly, to Totem-Pole power factor correction circuit.

Related Art

With the development trend of miniaturization, switching mode power supply must be high efficient for the sake of thermal dissipation. The traditional boost power factor correction (Boost PFC) circuit has large loss on the rectifier bridge, which occupies 20% or more of an overall loss of the switching mode power supply. How to reduce the loss of the rectifier bridge is essential for improving the efficiency of the switching mode power supply. Totem-Pole power factor correction (Totem-Pole PFC) circuit is widely used because the loss of the rectifier bridge is greatly reduced.

In the prior art, the filter circuit of the Totem-Pole PFC is generally arranged at AC input terminals and X-Cap must be used, which has very large size. In order to reduce the volume of the filter circuit, film capacitor can be used; one terminal of the film capacitor is coupled to the AC input terminals, and the other terminal of the film capacitor is coupled to the DC output terminals. However, when the output of the Totem-Pole PFC is under no-load or light-load, the voltage on the bus capacitor will be much higher than normal condition, which may result in explosion of the bus capacitor.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a novel power factor correction circuit for solving the deficiencies of the prior art.

First aspect of the present invention is to provide a power factor correction circuit, the power factor correction circuit includes: a first AC terminal and a second AC terminal for receiving an AC voltage; a first DC terminal and a second DC terminal for providing a DC voltage; a first bridge arm comprising a first switch and a second switch connected in series, a first node between the first switch and the second switch electrically coupled to the first AC terminal through a first inductor; a second bridge arm comprising a third switch and a fourth switch connected in series, a second node between the third switch and the fourth switch electrically coupled to the second AC terminal, the first bridge arm and the second bridge arm connected in parallel between the first DC terminal and the second DC terminal; a second inductor having one terminal connected to the first AC terminal, and another terminal connected to the first inductor; a first capacitor and/or a second capacitor, the first capacitor having one end connected to a third node between the second inductor and the first inductor, and another end connected to the first DC terminal, the second capacitor having one end connected to the third node between the second inductor and the first inductor, and another end connected to the second DC terminal; and a third capacitor and/or a fourth capacitor, the third capacitor connected in parallel to the third switch based on an arrangement of the second capacitor and having a capacitance value same as that of the second capacitor, the fourth capacitor connected in parallel to the fourth switch based on an arrangement of the first capacitor and having a capacitance value same as that of the first capacitor.

Second aspect of the present invention is to provide a power factor correction circuit, the power factor correction circuit includes: a first AC terminal and a second AC terminal for receiving an AC voltage; a first DC terminal and a second DC terminal for providing a DC voltage; a first bridge arm comprising a first switch and a second switch connected in series, a first node between the first switch and the second switch electrically coupled to the first AC terminal through a first inductor; a second bridge arm comprising a third switch and a fourth switch connected in series, a second node between the third switch and the fourth switch electrically coupled to the second AC terminal, the first bridge arm and the second bridge arm connected in parallel between the first DC terminal and the second DC terminal; a second inductor having one terminal connected to the first AC terminal and another terminal connected to the first inductor; a first switching unit and a first capacitor connected in series, and electrically connected between the first DC terminal and a third node between the second inductor and the first inductor; and/or a second switching unit and a second capacitor connected in series, and electrically connected between the second DC terminal and the third node between the second inductor and the first inductor, wherein the first switching unit and/or the second switching unit are turned off under light-load or no-load.

Third aspect of the present invention is to provide a power factor correction circuit, the power factor correction circuit includes: a first AC terminal and a second AC terminal for receiving an AC voltage; a first DC terminal and a second DC terminal for supplying a DC voltage; a first bridge arm comprising a first switch and a second switch connected in series, a first node between the first switch and the second switch electrically coupled to the first AC terminal through a first inductor; a second bridge arm comprising a third switch and a fourth switch connected in series, a second node between the third switch and the fourth switch electrically coupled to the second AC terminal, the first bridge arm and the second bridge arm connected in parallel between the first DC terminal and the second DC terminal; a second inductor having a first terminal connected to a first terminal of the first inductor, and connected to the first node between the first switch and the second switch, wherein the first inductor and the second inductor are coupled inductors, and the first terminal of the second inductor and the first terminal of the first inductor are terminals of same magnetic polarity; a first capacitor and/or a second capacitor, the first capacitor having one end connected to a second terminal of the second inductor, and another end connected to the first DC terminal, the second capacitor having one end connected to the second terminal of the second inductor, and another end connected to the second DC terminal; and a third capacitor and/or a fourth capacitor, the third capacitor connected in parallel to the third switch based on an arrangement of the second capacitor and having a capacitance value same as that of the second capacitor, the fourth capacitor connected in parallel to the fourth switch based on an arrangement of the first capacitor and having a capacitance value same as that of the first capacitor.

Fourth aspect of the present invention is to provide a power factor correction circuit, the power factor correction circuit includes: a first AC terminal and a second AC terminal for receiving an AC voltage; a first DC terminal and a second DC terminal for supplying a DC voltage; a first bridge arm comprising a first switch and a second switch connected in series, a first node between the first switch and the second switch electrically coupled to the first AC terminal through a first inductor; a second bridge arm comprising a third switch and a fourth switch connected in series, a second node between the third switch and the fourth switch electrically coupled to the second AC terminal, the first bridge arm and the second bridge arm connected in parallel between the first DC terminal and the second DC terminal; a second inductor having a first terminal connected to a first terminal of the first inductor, and connected to the first node between the first switch and the second switch, wherein the first inductor and the second inductor are coupled inductors, and the first terminal of the second inductor and the first terminal of the first inductor are terminals of same magnetic polarity; a first switching unit and a first capacitor connected in series, and electrically connected between a second terminal of the second inductor and the first DC terminal; and/or a second switching unit and a second capacitor connected in series, and electrically connected between the second terminal of the second inductor and the second DC terminal, wherein the first switching unit and/or the second switching unit are turned off under light-load or no-load.

The power factor correction circuit of the present invention can effectively prevent the voltage of the bus capacitor under no-load or light-load from exceeding a peak value of AC voltage at the AC input terminal by keeping the capacitors of the diagonal position of the rectifier bridge to have the same capacitance value, or turning off the switching unit connected in series with the capacitor under no-load or light-load.

The present invention is applicable to the Totem-Pole PFC circuit, and facilitates to reduce a volume of the filter circuit while preventing the sharp increase of the output voltage under no-load or light-load.

The additional aspects and advantages of the present invention are partially explained in the below description, and partially becoming apparent from the description, or can be obtained through practice of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The exemplary embodiments will be described in detail with reference to the accompanying drawings, through which the above and other features and advantages of the present invention will become more apparent.

FIG. 1 is a schematic diagram of a circuit structure of a power factor correction circuit according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a circuit structure of a power factor correction circuit according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram of a circuit structure of a power factor correction circuit according to a third embodiment of the present invention.

FIG. 4 is a schematic diagram of a circuit structure of a power factor correction circuit according to a fourth embodiment of the present invention.

FIG. 5 is a schematic diagram of a circuit structure of a power factor correction circuit according to a fifth embodiment of the present invention.

FIG. 6 is a schematic diagram of a circuit structure of a power factor correction circuit according to a sixth embodiment of the present invention.

FIG. 7 is a schematic diagram of a circuit structure of a power factor correction circuit according to a seventh embodiment of the present invention.

FIG. 8 is a schematic diagram of a circuit structure of a power factor correction circuit according to an eighth embodiment of the present invention.

FIG. 9 is a schematic diagram of a circuit structure of a power factor correction circuit according to a ninth embodiment of the present invention.

FIG. 10 is a schematic diagram of a circuit structure of a power factor correction circuit according to a tenth embodiment of the present invention.

FIG. 11 is a schematic diagram of a circuit structure of a power factor correction circuit according to an eleventh embodiment of the present invention.

FIG. 12 is a schematic diagram of a circuit structure of a power factor correction circuit according to a twelfth embodiment of the present invention.

FIG. 13A is a schematic diagram of a voltage waveform of a bus capacitor of a power factor correction circuit according to the prior art.

FIG. 13B is a schematic diagram of a voltage waveform of a bus capacitor of a power factor correction circuit according to the present invention.

DETAILED EMBODIMENTS OF THE INVENTION

The exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, the exemplary embodiments can be implemented in various forms and shall not be understood as being limited to the embodiments set forth herein; on the contrary, these embodiments are provided so that the invention will be thorough and complete, and the conception of exemplary embodiments will be fully conveyed to those skilled in the art. In the drawings, the same reference sign denotes the same or similar structure, so the detailed explanation will be omitted.

When element/component/and the like described and/or illustrated here are introduced, the phrases “one”, “a(an)”, “the”, “said” and “at least one” refer to one or more elements/components/and the like. The terms “include”, “comprise” and “have” refer to an open meaning without excluding additional element/component/and the like except for the listed element s/components/and the like. The relative phrases, such as, “upper” or “lower” used here may describe a relative relation of one component with respect to another component. It shall be understood that if the device illustrated in the drawing reverses to turn upside down, the component on an “upper” side will become a component on a “lower” side. In addition, the terms “first”, “second” and the like in the claims are not numeral limitations to object.

FIG. 1 illustrates a circuit structure of a power factor correction circuit according to a first embodiment of the present invention. The power factor correction circuit includes a first AC terminal AC₁ and a second AC terminal AC₂ for receiving an AC voltage, and a first DC terminal DC₁ and a second DC terminal DC₂ for providing a DC voltage. The power factor correction circuit further includes a first bridge arm, a second bridge arm, a first inductor L₁ and a second inductor L₂. The first bridge arm includes a first switch S₁ and a second switch S₂ connected in series. A first node N₁ between the first switch S₁ and the second switch S₂ is electrically coupled to the first AC terminal AC₁ through the first inductor L₁ and the second inductor L₂. The second bridge arm includes a third switch S₃ and a fourth switch S₄ connected in series. A second node N₂ between the third switch S₃ and the fourth switch S₄ is electrically coupled to the second AC terminal AC₂. The first bridge arm and the second bridge arm are connected in parallel between the first DC terminal DC₁ and the second DC terminal DC₂. The second inductor L₂ has two terminals, one terminal connected to the first AC terminal AC₁ and another terminal connected to the first inductor L₁.

The power factor correction circuit further includes a first capacitor C₁ and a second capacitor C₂. The first capacitor C₁ has one end connected to a third node N₃ between the second inductor L₂ and the first inductor L₁, and another end connected to the first DC terminal DC₁. The second capacitor C₂ has one end connected to the third node N₃ between the second inductor L₂ and the first inductor L₁, and another end connected to the second DC terminal DC₂.

The power factor correction circuit further includes a third capacitor C₃ and a fourth capacitor C₄. The third capacitor C₃ is connected in parallel to the third switch S₃ based on an arrangement of the second capacitor C₂, and has a capacitance value same as that of the second capacitor C₂. The fourth capacitor C₄ is connected in parallel to the fourth switch S₄ based on an arrangement of the first capacitor C₁, and has a capacitance value same as that of the first capacitor C₁.

In the present invention, the power factor correction circuit may further include a first surge diode D₁ and a second surge diode D₂ connected in series. A cathode of the first surge diode D₁ is connected to the first DC terminal DC₁, an anode of the second surge diode D₂ is connected to the second DC terminal DC₂, and an anode of the first surge diode D₁ and a cathode of the second surge diode D₂ are connected to the first AC terminal AC₁.

In the present invention, the power factor correction circuit may further include a bus capacitor C_(bus) electrically connected between the first DC terminal DC₁ and the second DC terminal DC₂.

In the embodiment of FIG. 1, the third switch S₃ and the fourth switch S₄, may be, for example, diodes. In other embodiment, the first switch S₁, the second switch S_(z), the third switch S₃ and the fourth switch S₄ may be semiconductor switching devices, for example, including but not limited to MOSFETs, GaN devices, or SiC devices.

FIG. 2 illustrates a circuit structure of a power factor correction circuit according to a second embodiment of the present invention, which differs from the embodiment of FIG. 1 in that the power factor correction circuit only includes the second capacitor C₂ and the third capacitor C₃ corresponding to the second capacitor C₂. The second capacitor C₂ has one end connected to the third node N₃ between the second inductor L₂ and the first inductor L₁, and another end connected to the second DC terminal DC₂. The third capacitor C₃ is connected in parallel to the third switch S₃ based on the arrangement of the second capacitor C₂, and has a capacitance value same as that of the second capacitor C₂.

FIG. 3 illustrates a circuit structure of a power factor correction circuit according to a third embodiment of the present invention, which differs from the embodiment of FIG. 1 in that the power factor correction circuit only includes the first capacitor C₁ and the fourth capacitor C₄ corresponding to the first capacitor C₁. The first capacitor C₁ has one end connected to the third node N₃ between the second inductor L₂ and the first inductor L₁, and another end connected to the first DC terminal DC₁. The fourth capacitor C₄ is connected in parallel to the fourth switch S₄ based on the arrangement of the first capacitor C₁, and has a capacitance value same as that the first capacitor C₁.

FIG. 4 illustrates a circuit structure of a power factor correction circuit according to a fourth embodiment of the present invention, which differs from the embodiment of FIG. 1 in that the third capacitor C₃ and the fourth capacitor C₄ are omitted while the switching units connected in series to the first and second capacitors and turned off under no-load or light-load are provided. More specifically, the power factor correction circuit includes a first switching unit SW₁ and a first capacitor C₁ connected in series, and a second switching unit SW₂ and a second capacitor C₂ connected in series. The first switching unit SW₁ and the first capacitor C₁ are electrically connected between the first DC terminal DC₁ and the third node N₃ between the second inductor L₂ and the first inductor L₁. The second switching unit SW₂ and the second capacitor C₂ are electrically connected between the second DC terminal DC₂ and the third node N₃ between the second inductor L₂ and the first inductor L₁. The first switching unit SW₁ and the second switching unit SW₂ are turned off under light-load or no-load.

FIG. 5 illustrates a circuit structure of a power factor correction circuit according to a fifth embodiment of the present invention, which differs from the embodiment of FIG. 4 in that the power factor correction circuit only includes the second switching unit SW₂ and the second capacitor C₂ connected in series. The second switching unit SW₂ and the second capacitor C₂ are electrically connected between the second DC terminal DC₂ and the third node N₃ between the second inductor L₂ and the first inductor L₁. The second switching unit SW₂ is turned off under light-load or no-load.

FIG. 6 illustrates a circuit structure of a power factor correction circuit according to a sixth embodiment of the present invention, which differs from the embodiment of FIG. 4 in that the power factor correction circuit only includes the first switching unit SW₁ and the first capacitor C₁ connected in series. The first switching unit SW₁ and the first capacitor C₁ are electrically connected between the first DC terminal DC₁ and the third node N₃ between the second inductor L₂ and the first inductor L₁. The first switching unit SW₁ is turned off under light-load or no-load.

In some embodiments, the first switching unit and the second switching unit may include one or more switches.

In some embodiments, a load less than 50% of a rated load may be considered as the light-load, but the present application is not limited thereto. In some embodiments, light-load may refer to a load less than 30%, 20% or 5% of the rated load.

FIG. 7 illustrates a circuit structure of a power factor correction circuit according to a seventh embodiment of the present invention, which differs from the embodiment of FIG. 1 in that the first node N₁ between the first switch S₁ and the second switch S₂ of the first bridge arm of the power factor correction circuit is electrically connected to the first AC terminal AC₁ through the first inductor L₁, i.e., the first inductor L₁ has a first terminal connected to the first node N₁ and a second terminal connected to the first AC terminal AC₁; a first terminal of the second inductor L₂ is connected to the first terminal of the first inductor L₁, and connected to the first node N₁ between the first switch S₁ and the second switch S₂; the first capacitor C₁ has one end connected to a second terminal N₄ of the second inductor L₂ and another end connected to the first DC terminal DC₁; and the second capacitor C₂ has one end connected to the second terminal N₄ of the second inductor L₂ and another end connected to the second DC terminal DC₂. In the embodiment of FIG. 7, the power factor correction circuit further includes a third capacitor C₃ and a fourth capacitor C₄. The third capacitor C₃ is connected in parallel to the third switch S₃ based on an arrangement of the second capacitor C₂, and has a capacitance value same as that of the second capacitor C₂. The fourth capacitor C₄ is connected in parallel to the fourth switch S₄ based on an arrangement of the first capacitor C₁, and has a capacitance value same as that of the first capacitor C₁. The first inductor L₁ and the second inductor L₂ are coupled inductors, and the first terminal of the first inductor L₁ and the first terminal of the second inductor L₂ are terminals of same magnetic polarity.

FIG. 8 illustrates a circuit structure of a power factor correction circuit according to an eighth embodiment of the present invention, which differs from the embodiment of FIG. 7 in that the power factor correction circuit only includes the second capacitor C₂ and the third capacitor C₃ corresponding to the second capacitor C₂. The second capacitor C₂ has one end connected to the second terminal N₄ of the second inductor L₂, and another end connected to the second DC terminal DC₂. The third capacitor C₃ is connected in parallel to the third switch S₃ based on the arrangement of the second capacitor C₂, and has a capacitance value same as that of the second capacitor C₂.

FIG. 9 illustrates a circuit structure of a power factor correction circuit according to a ninth embodiment of the present invention, which differs from the embodiment of FIG. 7 in that the power factor correction circuit only includes the first capacitor C₁ and the fourth capacitor C₄ corresponding to the first capacitor C₁. The first capacitor C₁ has one end connected to the second terminal N₄ of the second inductor L₂, and another end connected to the first DC terminal DC₁. The fourth capacitor C₄ is connected in parallel to the fourth switch S₄ based on the arrangement of the first capacitor C₁, and has a capacitance value same as that of the first capacitor C₁.

FIG. 10 illustrates a circuit structure of a power factor correction circuit according to a tenth embodiment of the present invention, which differs from the embodiment of FIG. 7 in that the third capacitor C₃ and the fourth capacitor C₄ are omitted while the switching units connected in series to the first and second capacitors and turned off under no-load or light-load are provided. More specifically, the power factor correction circuit includes a first switching unit SW₁ and a first capacitor C₁ connected in series, and a second switching unit SW₂ and a second capacitor C₂ connected in series. The first switching unit SW₁ and the first capacitor C₁ are electrically connected between the second terminal N₄ of the second inductor L₂ and the first DC terminal DC₁. The second switching unit SW₂ and the second capacitor C₂ are electrically connected between the second terminal N₄ of the second inductor L₂ and the second DC terminal DC₂. The first switching unit SW₁ and the second switching unit SW₂ are turned off under light-load or no-load.

FIG. 11 illustrates a circuit structure of a power factor correction circuit according to an eleventh embodiment of the present invention, which differs from the embodiment of FIG. 10 in that the power factor correction circuit only includes the second switching unit SW₂ and the second capacitor C₂ connected in series. The second switching unit SW₂ and the second capacitor C₂ are electrically connected between the second terminal N₄ of the second inductor L₂ and the second DC terminal DC₂. The second switching unit SW₂ is turned off under light-load or no-load.

FIG. 12 illustrates a circuit structure of a power factor correction circuit according to a twelfth embodiment of the present invention, which differs from the embodiment of FIG. 10 in that the power factor correction circuit only includes the first switching unit SW₁ and the first capacitor C₁ connected in series. The first switching unit SW₁ and the first capacitor C₁ are electrically connected between the second terminal N₄ of the second inductor L₂ and the first DC terminal DC₁. The first switching unit SW₁ is turned off under light-load or no-load.

In some embodiments, the first switching unit and the second switching unit may include one or more switches.

Similarly, a load less than 50% of a rated load may be considered as the light-load, but the present application is not limited thereto. In some embodiments, the light-load may refer to a load less than 30%, 20% or 5% of the rated load. In the above embodiments, the third switch S₃ and the fourth switch S₄ may be, for example, diodes. In other embodiment, the first switch S₁, the second switch S₂, the third switch S₃ and the fourth switch S₄ may be semiconductor switching devices, for example, including but not limited to MOSFETs, GaN devices, or SiC devices.

FIG. 13A is a schematic diagram of a voltage waveform of bus capacitor of a power factor correction circuit according to the prior art, and FIG. 13B is a schematic diagram of a voltage waveform of bus capacitor of a power factor correction circuit according to the present invention. As shown in FIGS. 13A and 13B, when the circuit is under no-load or light-load, a voltage V_(bus) of the bus capacitor C_(bus) of the prior art increases, but a voltage V_(bus) of the bus capacitor C_(bus) of the present invention does not increase, such that the bus capacitor can be effectively protected. The power factor correction circuit of the present invention can effectively prevent the voltage of the bus capacitor from increasing abnormally when the circuit is under no-load or light-load by keeping the capacitors of the diagonal position of the rectifier bridge to have the same capacitance value, or by connecting the switching unit in series to the capacitor and turning off the switching unit under no-load or light-load.

The present invention is applicable to the Totem-Pole PFC circuit, and facilitates to reduce a volume of the filter circuit while preventing a sharp increase of the output voltage of the bus capacitor under no-load or light-load.

Exemplary embodiments of the present invention have been shown and described above. It shall be understood that the present invention is not limited to the disclosed embodiments. Instead, the present invention intends to cover various modifications and equivalents included in the spirit and scope of the appended claims. 

What is claimed is:
 1. A power factor correction circuit, comprising: a first AC terminal and a second AC terminal for receiving an AC voltage; a first DC terminal and a second DC terminal for providing a DC voltage; a first inductor; a first bridge arm comprising a first switch and a second switch connected in series, a first node between the first switch and the second switch electrically coupled to the first AC terminal through the first inductor; a second bridge arm comprising a third switch and a fourth switch connected in series, a second node between the third switch and the fourth switch electrically coupled to the second AC terminal, wherein the first bridge arm and the second bridge arm are connected in parallel between the first DC terminal and the second DC terminal; a second inductor having one terminal connected to the first AC terminal, and another terminal connected to the first inductor; a first capacitor and/or a second capacitor, the first capacitor having one end connected to a third node between the second inductor and the first inductor and another end connected to the first DC terminal, the second capacitor having one end connected to the third node between the second inductor and the first inductor and another end connected to the second DC terminal; and a third capacitor and/or a fourth capacitor, the third capacitor connected in parallel to the third switch based on an arrangement of the second capacitor and having a capacitance value same as that of the second capacitor, the fourth capacitor connected in parallel to the fourth switch based on an arrangement of the first capacitor and having a capacitance value same as that of the first capacitor.
 2. The power factor correction circuit of claim 1, further comprising a first surge diode and a second surge diode connected in series, a cathode of the first surge diode connected to the first DC terminal, an anode of the second surge diode connected to the second DC terminal, and an anode of the first surge diode and a cathode of the second surge diode connected to the first AC terminal.
 3. The power factor correction circuit of claim 1, further comprising a bus capacitor electrically connected between the first DC terminal and the second DC terminal.
 4. The power factor correction circuit of claim 1, wherein each of the third switch and the fourth switch is a diode.
 5. The power factor correction circuit of claim 1, wherein each of the first switch, the second switch, the third switch and the fourth switch is a semiconductor switching device including a MOSFET, a GaN device, or a SiC device.
 6. A power factor correction circuit, comprising: a first AC terminal and a second AC terminal for receiving an AC voltage; a first DC terminal and a second DC terminal for providing a DC voltage; a first inductor; a first bridge arm comprising a first switch and a second switch connected in series, a first node between the first switch and the second switch electrically coupled to the first AC terminal through the first inductor; a second bridge arm comprising a third switch and a fourth switch connected in series, a second node between the third switch and the fourth switch electrically coupled to the second AC terminal, wherein the first bridge arm and the second bridge arm are connected in parallel between the first DC terminal and the second DC terminal; a second inductor having one terminal connected to the first AC terminal and another terminal connected to the first inductor; a first switching unit and a first capacitor connected in series, and electrically connected between the first DC terminal and a third node between the second inductor and the first inductor; and/or a second switching unit and a second capacitor connected in series, and electrically connected between the second DC terminal and the third node between the second inductor and the first inductor, wherein the first switching unit and/or the second switching unit are turned off under light-load or no-load.
 7. The power factor correction circuit of claim 6, further comprising a bus capacitor electrically connected between the first DC terminal and the second DC terminal.
 8. The power factor correction circuit of claim 6, further comprising a first surge diode and a second surge diode connected in series, a cathode of the first surge diode connected to the first DC terminal, an anode of the second surge diode connected to the second DC terminal, and an anode of the first surge diode and a cathode of the second surge diode connected to the first AC terminal.
 9. The power factor correction circuit of claim 6, wherein each of the third switch and the fourth switch is a diode.
 10. The power factor correction circuit of claim 6, wherein each of the first switch, the second switch, the third switch and the fourth switch is a semiconductor switching device including a MOSFET, a GaN device, or a SiC device.
 11. A power factor correction circuit, comprising: a first AC terminal and a second AC terminal for receiving an AC voltage; a first DC terminal and a second DC terminal for supplying a DC voltage; a first inductor; a first bridge arm comprising a first switch and a second switch connected in series, a first node between the first switch and the second switch electrically coupled to the first AC terminal through the first inductor; a second bridge arm comprising a third switch and a fourth switch connected in series, a second node between the third switch and the fourth switch electrically coupled to the second AC terminal, wherein the first bridge arm and the second bridge arm are connected in parallel between the first DC terminal and the second DC terminal; a second inductor having a first terminal connected to a first terminal of the first inductor and connected to the first node between the first switch and the second switch, wherein the first inductor and the second inductor are coupled inductors, and the first terminal of the second inductor and the first terminal of the first inductor are terminals of same magnetic polarity; a first capacitor and/or a second capacitor, the first capacitor having one end connected to a second terminal of the second inductor and another end connected to the first DC terminal, the second capacitor having one end connected to the second terminal of the second inductor and another end connected to the second DC terminal; and a third capacitor and/or a fourth capacitor, the third capacitor connected in parallel to the third switch based on an arrangement of the second capacitor and having a capacitance value same as that of the second capacitor, the fourth capacitor connected in parallel to the fourth switch based on an arrangement of the first capacitor and having a capacitance value same as that of the first capacitor.
 12. The power factor correction circuit of claim 11, further comprising a bus capacitor electrically connected between the first DC terminal and the second DC terminal.
 13. The power factor correction circuit of claim 11, further comprising a first surge diode and a second surge diode connected in series, a cathode of the first surge diode connected to the first DC terminal, an anode of the second surge diode connected to the second DC terminal, and an anode of the first surge diode and a cathode of the second surge diode connected to the first AC terminal.
 14. The power factor correction circuit of claim 11, wherein each of the third switch and the fourth switch is a diode.
 15. The power factor correction circuit of claim 11, wherein each of the first switch, the second switch, the third switch and the fourth switch is a semiconductor switching device including a MOSFET, a GaN device, or a SiC device.
 16. A power factor correction circuit, comprising: a first AC terminal and a second AC terminal for receiving an AC voltage; a first DC terminal and a second DC terminal for providing a DC voltage; a first inductor; a first bridge arm comprising a first switch and a second switch connected in series, a first node between the first switch and the second switch electrically coupled to the first AC terminal through the first inductor; a second bridge arm comprising a third switch and a fourth switch connected in series, a second node between the third switch and the fourth switch electrically coupled to the second AC terminal, wherein the first bridge arm and the second bridge arm are connected in parallel between the first DC terminal and the second DC terminal; a second inductor having a first terminal connected to a first terminal of the first inductor and connected to the first node between the first switch and the second switch, wherein the first inductor and the second inductor are coupled inductors, and the first terminal of the second inductor and the first terminal of the first inductor are terminals of same magnetic polarity; a first switching unit and a first capacitor connected in series, and electrically connected between a second terminal of the second inductor and the first DC terminal; and/or a second switching unit and a second capacitor connected in series, and electrically connected between the second terminal of the second inductor and the second DC terminal, wherein the first switching unit and/or the second switching unit are turned off under light-load or no-load.
 17. The power factor correction circuit of claim 16, further comprising a bus capacitor electrically connected between the first DC terminal and the second DC terminal.
 18. The power factor correction circuit of claim 16, further comprising a first surge diode and a second surge diode connected in series, a cathode of the first surge diode connected to the first DC terminal, an anode of the second surge diode connected to the second DC terminal, and an anode of the first surge diode and a cathode of the second surge diode connected to the first AC terminal.
 19. The power factor correction circuit of claim 16, wherein each of the third switch and the fourth switch is a diode.
 20. The power factor correction circuit of claim 16, wherein each of the first switch, the second switch, the third switch and the fourth switch is a semiconductor switching device including a MOSFET, a GaN device, or a SiC device. 